Justin was a part of the Baltimore Raven and Detroit Lions practice squads respectively the past couple of years. Boren was designated "waived/injured" which means he faced the possibility of being claimed by another team. Since he cleared the waiver process, the Broncos had two options 1) place him on the Injured Reserve list 2) reach an injury settlement with him. The "injured" designation is just to let other teams know that the player is hurt. It does not stop them from putting in a waiver claim. Because Boren cleared waivers the Broncos were then free to put him on IR. He does not count against the active number of players on the Broncos roster.
Justin had been listed as the 3rd string LG behind Zane Beadles and Quentin Saulsberry.